Comparative thermal performance among four young-of-the-year temperate reef fish species

Identifying the role of temperature on species-specific performance is critical for predicting how species will respond to temperature increases expected under climate change. We compared the thermal performance of two sympatric Pacific rockfish species complexes (controls for relatedness and geographic location) that vary in larval life-history traits associated with different oceanographic regimes including temperature during early life-history stages: the BY complex (Black: Sebastes melanops, Yellowtail: S. flavidus) and the CQ complex (Copper: S. caurinus, Quillback: S. maliger). By using controlled experiments, we evaluated foraging activity, growth, and survival of young-of-the-year rockfish recruits under current and future habitat temperatures over a 14-day time period indicative of marine heatwave events expected with climate change. BY rockfish displayed a heat-intolerant behaviour by only foraging at temperatures within current habitat temperatures, whereas the CQ rockfish displayed a heat-tolerant behaviour by actively foraging at temperatures above current and future predicted temperatures for a limited time. Although growth and survival in each species significantly declined with temperature, the magnitude of the effect did not vary between species. Taken together, our results show that rockfish are capable of using different behavioural strategies to cope with warming and may be differentially impacted by future climate conditions.